You can already see the shape of that future in Google's Chrome OS. This is a very much "locked down" combination of operating system, browser, cloud applications, and storage. Security updates are automatic and (eventually) involuntary. You are limited to running the software that Google allows you to run, most of which is executed on Google servers. No website Java programs are allowed at all.
Such an architecture provides for maximum security and has the advantage of minimum hardware requirements for ram memory and on-machine storage. It allows for encryption of all communications between your computer and the outside world with mimimum involvement or decison making by the user. And from Google's point of view it represents the perfect vehicle for advertizing in a controlled enviornment. In a sense, your computer has already been hacked (by Google) when you buy it. And they will make sure it stays hacked to their preferences.
The next step will be integration of the computer operating system with the phone operating environment. The two will merge with more software coming from "app stores" and not from the wild. At the same time, the services on the computer will become more integrated with each other so that social media, calendar, voice calls, texting, and social media work togerther and don't work at all with outside software. It becomes a secure walled garden with enough internal features and flexibility to be tolerable to the mass users who are not or can not be responsible for their own security.